The present invention deals with a system for treating an object in a body tract. More specifically, the present invention deals with a system for immobilizing or manipulating an object, such as a stone, to better accommodate treatment of the object.
Objects, such as stones, can reside in the kidney, ureter, or biliary duct. Such stones can be extremely painful and require medical treatment. Removal of such stones has been accomplished by two methods in the past. The first method is removal through conventional surgery. Such a treatment has obvious disadvantages, risks and drawbacks. The second method is removal under the guidance of an endoscope. A grasping device is guided through the bodily tract to the site of the stone and is used to grasp and remove the stone under endoscopic guidance. Examples of grasping devices which have been used in the past for the removal of stones include forceps with axially-directed grasping arms, and basket devices such as shown in the Segura et al. U.S. Pat. No. 4,590,938.
Another prior means of treating stones includes directing a force against the stone within the duct to break the stone into pieces so that it can be more easily passed or removed. There are currently many different methods employed to direct force against a stone. One such method is set out in U.S. Pat. No. 5,160,336, entitled "DEVICE FOR ACTING BY ULTRASONIC VIBRATIONS ON AN OBJECT," which is incorporated by reference herein. In order to more efficiently break the stone, attempts have been made to immobilize the stone while the breaking force is imparted on the stone. This provides a more efficient system because the energy directed toward the stone during application of the breaking force is not dissipated through movement of the stone. Instead, the stone is forced to absorb a greater portion of the energy and thereby break more readily.
Prior attempts to immobilize the stone during treatment have included placing an inflatable balloon behind the stone in the duct to provide a "backstop" for the stone. However, such balloons require inflation lumens, seals, relatively time consuming inflation and deflation steps, and are sensitive to inflation pressures. The balloons are susceptible to puncture or rupture which is undesirable. Further, the balloons completely occlude the ureter (or other bodily passage) which can also have disadvantages. In addition, the balloons provide an extremely elastic backstop so that an undesirably high amount of the force imparted on the stone is dissipated in the elasticity of the balloon.
Another method of immobilizing the stone during treatment has been to use a basket, such as that set out in U.S. Pat. No. 4,590,938. The treating physician captures the stone in the basket and then attempts to break the stone into pieces. However, such baskets do not provide efficient filtering in that smaller stone particles can slip through the basket. In addition, such baskets, in order to immobilize the stone, must be positioned around the stone. This reduces access to the surface of the stone by any other end effectuating device such as a treating laser or probe. This tends to make the operation more difficult and increases the potential risk of damage to the tract. Further, crushing baskets which are sometimes used to crush gall stones cannot be practically used in the urinary tract to crush kidney stones because of the great amount of crushing force which is required. Attempting to exert such force on a kidney stone with a crushing basket would substantially increase the risk of damage to the urinary tract.